The aim of this research is two fold. One is to study the mechanism of synthesis of DNA in vitro and the other is to study the mechanism of inhibition of DNA synthesis by some antitumor drugs. As we dissect the process of DNA replication which we are able to do in this in vitro system, we will try to find out the effect of the antitumor drugs on each step. Among the drugs we will be investigating are ara CTP, nogolamycin, hedamycin, and chromomycin. We would like to complete the isolation of the gene products of dna A, B, C, D and G. This can be done by complementation with normal protein of a cell free system which is temperature sensitive for the conversion of 0X174 single stranded circular DNA to its nicked double stranded replicative form. We would also like to study and isolate the proteins required for M13 DNA synthesis in vitro. Among some of the enzymes of interest is the rifamycin resistant RNA polymerase which we would like to isolate.